What is a Road Roller?
Road rollers are most commonly used for building roads or to produce compact foundations for vast areas, but they may also be utilized in a variety of other applications, such as landfills and agricultural projects.
The primary function of a road roller is to apply direct pressure on loose materials in order to crush, knead, or vibrate them. The rolling process compacts weakly bonded foundation materials, so that they stay compact and do not fall apart. Different types of road rollers are available to meet various construction demands. Each one is explained further down.
Different Types of Road Rollers
The following are different types of road rollers used in construction:
1. Grid Roller
- These road rollers feature a cylinder-shaped heavy steel surface with a grid of steel bars with tiny holes, and they may be ballasted with concrete blocks.
- They are usually towed and may go at speeds ranging from 5 to 24 km/h.
- Weights typically range from 5 to 15 tonnes net and ballasted.
- Grid rollers compress most coarse-grained soils by providing strong contact pressure but little kneading action.
2. Smooth Wheeled Roller
- The front end of this roller has a big steel drum, while the back end has one or two wheels or drums. It can be one of two varieties, depending on the number of wheels on the back:
- Rollers in pairs (having one wheel at the rear and one wheel in front)
- Rollers with three wheels (having two wheels at the rear and one in front)
- Tandem rollers weigh between 2 and 8 tonnes, whereas two-wheeled rollers weigh between 8 and 10 tonnes.
- A smooth wheeled roller provides 100 percent ground covering.
- Filling the inner space of the drum with water or wet sand can increase the roller’s weight. This is referred to as ballasting.
- Tandem rollers exert a ground pressure of roughly 10 to 17 kg/cm2.
- The load per centimeter breadth and diameter of the smooth wheel roller determine its performance.
- The kind of soil to be compacted and project requirements determine the speed and number of passes of a smooth wheeled roller. The ideal operating speed is 3 to 6 km/h, and around 8 passes are sufficient for compacting a 20 cm layer.
- Stone soling, gravel, sand, hardcore, ballast, and surface treatments are best consolidated with smooth wheel rollers. Although they are not good for consolidating embankments or soft sub-grades, they are better than any other plant for compacting silty and sandy soils and with fewer passes than any other plant. It will compress more easily if the moisture content is somewhat higher than ideal.
- The two types (steam and diesel) are quite similar, with the primary variation being the power units. Adjustable weight devices that may be added to the wheels to vary the rolling pressure to suit various consolidation needs are available. The sliding weights must always be near the back of the roller while doing heavy work. When the roller is on a gradient, the sliding weight must never be changed.
- The steam road roller can withstand more wear and tear and is much easier to operate than the diesel road roller, but it takes over an hour to start up and cannot be turned off temporarily, whereas the diesel road roller can be started and shut down in a matter of minutes and does not consume fuel when standing idle on a job. Road rollers powered by steam are becoming obsolete. Diesel rollers are less expensive to operate.
- Some rollers have their prime movers or engines installed on the roller as a separate unit, which is a tractor and has its benefits.
- For scraping off the mud and keeping the wheels clean while rolling, scrappers are placed on all of the wheels at adjustable positions across the whole width of the roll, with a water spraying mechanism.
- A road roller can climb a maximum of 1 in 5 grades.
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3. Pneumatic Tired Roller
- A highly loaded wagon with numerous rows of four to six closely spaced tires makes up this type of road roller. A rubber-tired roller is another name for this.
- It applied consistent pressure over the whole breadth.
- The following are two elements that influence the degree of compaction:
- Tyre pressure
- Area of contact
- Tyre pressures of up to 7 kg/cm2 are possible.
- The coverage area is around 80%.
- The roller’s gross weight is around 6 to 10 tonnes, but it may be raised to 25 tonnes by ballasting with steel sections or other methods.
- With eight passes of the roller, the maximum density may be attained. The roller’s best speed is between 6 and 24 km/h.
- Compacts cold-applied bituminous pavements, soft base course materials, and loose soil layers. These rollers may also compress closely graded sands and fine-grained cohesive soils at moisture levels nearing their plastic limits, however, the compaction is not as good as with a smooth wheel roller.
- They’re especially useful for finishing off an embankment compacted with a sheepsfoot roller or on loose sandy soils.
4. Sheepsfoot Roller
- This type of roller, as the name implies, comprises a drum with several round or rectangular-shaped protrusions or “feet” on it. Tamping rollers are another name for these rollers.
- Drums of various diameters and widths, as well as varying lengths and forms of feet, are available. The most common kind features two 1.22-meter-wide and 1.06-meter-long drums that are either taper-foot or club-foot rollers, depending on the curvature of the feet.
- Each protrusion can range in size from 30 to 80 cm2.
- The coverage area is around 8% to 12%.
- The compacting layer should be roughly 5 cm thicker than the length of each foot.
- This type of roller is mostly used for the compaction of cohesive soils such as heavy clays and silty clays. Not effective with sandy soils.
- By filling the drum with water or moist sand, the weight of the drum may be increased.
- The factors that govern the amount of compaction of soil are as follow:
- The gross weight of the roller
- Area of each foot
- No of feet or lugs in contact with the ground
- Total no of feet per drum
- Maximum pressure is exerted on the soil when a foot is vertical.
- When the impression made by the projecting teeth is less than 12 mm deep or the surface has been rolled 16 to 20 times, the soil is said to have consolidated.
- To provide comprehensive coverage, 10 to 20 passes are usually necessary.
- Consolidated dirt should have a density of around 1.48 kg/cm3. With a smooth wheel roller, the top layer must be completed. Filling the drum with wet sand or some other substance will increase the pressure on the feet.
5. Single Drum Roller
- A single drum roller is a significant piece of machinery.
- The front has a large drum, while the back has distinctive tires. These tires are more resistant to punctures and can help you prevent most flats.
- When working on construction sites and roadways, you’ll need these heavy-duty tires. The driver sits in the center part of the single drum roller. Modern versions come in three distinct configurations to fulfill the demands of every surface compaction application.
- The use of top-of-the-line components assures great performance and dependability. The front scraper is strengthened, the drum is 32 mm thick, and the turbocharger has a pre-cleaner. These are only a few instances of the design-for-quality approach.
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6. Double Drum Roller
- The modern double drum asphalt roller line includes everything from small machines for little operations to huge machines for massive projects.
- Vibration-dampening platforms, swivel chairs for greater sight, logically organized controls, and Roll Over Protective Structures (ROPS) all help with mobility, operator ergonomics, and safety.
7. Vibratory Roller
- Vibratory Rollers are generally used in road and highway construction to crush loose dirt or asphalt.
- Ground compaction/stabilization is another application for these devices on building sites.
- Companies now make soil compactors weighing 10 to 12 tonnes, as well as 3.5 to 9 tonne tandem compactors with sophisticated features, which are used to crush loose dirt or asphalt and are mostly utilized for road and highway building.
- Ground compaction/stabilization is another application for these devices on building sites. We can now obtain tandem compactors with modern features that weigh 3.5 tonnes and 9 tonnes.
How does the road roller work?
Road rollers may utilize the vehicle’s weight to compress the surface being rolled (static) or use mechanical advantage to compress the surface being rolled (dynamic) (vibrating).